GPS data source changed for unknown reason

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Squirry
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GPS data source changed for unknown reason

Post by Squirry »

I used HLT v23.0.11 at a track day for the second time yesterday.

On both occasions, I've used a GoPro Hero8 black as the external camera, and a Dual XGPS160 connected via Bluetooth to my iPhone Xs Max (currently on iOS 13.6).

On the previous occasion, everything worked well and the only problem I spotted in the data after the event was due to inaccurate calibration of the accelerometer in my phone.

Looking at the data from yesterday's session, it appears that something unexpected has occured.

There were 6 sessions, each of 5-6 laps.

During the first session, the GPS data was recorded at 10 Hz from the external GPS, as was the case for all sessions of my previous track day.

However sessions 2-6 yesterday show 1 Hz data from the iPhone's GPS.

I didn't spot any indications that the GPS data source had switched.

Is anyone able to suggest to me:

1 - Possible causes for the GPS source to change?
2 - What I should look for in future before leaving the pits to ensure that the data source is correct?
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Harry
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Re: GPS data source changed for unknown reason

Post by Harry »

LapTimer is falling back to internal sensors in case external sensors disconnect. This is to make sure you get recordings at all. There is no health check included warning you when a disconnect happens. LapTimer will show a short pop up when the GPS source changes, but that’s easy to miss.

I could add a warning (yellow alert) in case an external has been connected but isn’t anymore. This condition would be reset once LapTimer is restarted or the time passed is bigger than eg an hour?

Reasons for disconnects can be various: drained battery, some problem with the Bluetooth stack, a lock up of the external device, some conflicts between wireless devices. Hard to investigate after the fact...

Harry
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Squirry
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Re: GPS data source changed for unknown reason

Post by Squirry »

Thanks, that makes sense.
What could I check before leaving the pits each time to ensure the correct source is being used?
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Harry
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Re: GPS data source changed for unknown reason

Post by Harry »

Squirry wrote: Thu Aug 13, 2020 8:53 am Thanks, that makes sense.
What could I check before leaving the pits each time to ensure the correct source is being used?
For v23, you need to follow Administration ‣ Sensor List to see which sensors are connected and used currently. I have added an additional health check this morning showing a warning in case an external GPS or OBD sensor has been connected but isn't any more. This will get available for v24. You can join the beta in case this is critical fro you. See the announcements section here on the forum.

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Squirry
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Re: GPS data source changed for unknown reason

Post by Squirry »

Fantastic, thanks!
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